All of the invoices for each of the payments you made for your Pro plan are available for download within your dashboard.
You'll be able to find them by hovering over your profile picture in the dashboard, and clicking "My Pro plan payments"
You can also access it in the Configure tab of your bot, by clicking the "Payments" button
You can download each of the invoices by clicking the gray icon. It will be delivered to the email address you defined in your "Billing details"
If you want to change this email address, or if you want to add your company data to your invoices, just click "Billing details" in your Configure tab.